[20250701] BOJ / G3 / 웜홀 / 설진영

Seol-JY/202507/1 BOJ G3 웜홀.md

@@ -0,0 +1,102 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        int TC = nextInt(new StringTokenizer(br.readLine()));
+
+        while (TC-- > 0) {
+            StringTokenizer st = new StringTokenizer(br.readLine());
+            int N = nextInt(st);
+            int M = nextInt(st);
+            int W = nextInt(st);
+
+            List<Edge>[] graph = new ArrayList[N + 1];
+            for (int i = 1; i <= N; i++) {
+                graph[i] = new ArrayList<>();
+            }
+
+            for (int i = 0; i < M; i++) {
+                st = new StringTokenizer(br.readLine());
+                int s = nextInt(st);
+                int e = nextInt(st);
+                int t = nextInt(st);
+
+                graph[s].add(new Edge(e, t));
+                graph[e].add(new Edge(s, t));
+            }
+
+            for (int i = 0; i < W; i++) {
+                st = new StringTokenizer(br.readLine());
+                int s = nextInt(st);
+                int e = nextInt(st);
+                int t = nextInt(st);
+
+                graph[s].add(new Edge(e, -t));
+            }
+
+            if (hasNegativeCycle(graph, N)) {
+                System.out.println("YES");
+            } else {
+                System.out.println("NO");
+            }
+        }
+    }
+
+    static boolean hasNegativeCycle(List<Edge>[] graph, int N) {
+        long[] dist = new long[N + 1];
+        final long INF = 987654321
+        Arrays.fill(dist, INF);
+
+        for (int start = 1; start <= N; start++) {
+            if (dist[start] != INF) continue;
+
+            dist[start] = 0;
+
+            boolean updated = false;
+            for (int i = 0; i < N - 1; i++) {
+                updated = false;
+                for (int j = 1; j <= N; j++) {
+                    if (dist[j] == INF) continue;
+
+                    for (Edge edge : graph[j]) {
+                        if (dist[j] + edge.cost < dist[edge.to]) {
+                            dist[edge.to] = dist[j] + edge.cost;
+                            updated = true;
+                        }
+                    }
+                }
+                if (!updated) break;
+            }
+
+            for (int j = 1; j <= N; j++) {
+                if (dist[j] == INF) continue;
+
+                for (Edge edge : graph[j]) {
+                    if (dist[j] + edge.cost < dist[edge.to]) {
+                        return true;
+                    }
+                }
+            }
+        }
+
+        return false;
+    }
+
+    static class Edge {
+        int to, cost;
+
+        Edge(int to, int cost) {
+            this.to = to;
+            this.cost = cost;
+        }
+    }
+
+    static int nextInt(StringTokenizer st) {
+        return Integer.parseInt(st.nextToken());
+    }
+}
+```